Barry and Iris are attending the activation of the particle accelerator when someone steals Iris's bag in pilot episode. Hartley Rathaway shows Cisco some evidence of the fate of Ronnie in episode 1x12 "Crazy for You". From episode 1x13 "The Nuclear Man". The Flash team watches Ray Palmer's arrival here with Felicity in episode 1x18 "All Star Team Up".
Etta and Simon talk about the discovery of Walter's body in episode #419 "Letters of Transit". Filmed in the CBC Breezeway.
From episode #418 "The Consultant".
Eobard Thawne, posing as a NASA medical officer, talks to an astronaut who is set to travel on Apollo 13 in episode 2x13 "Land of the Lost". The Legends infiltrate the NASA complex and track down Henry Heywood. Stein and Rory end up watching the events of Apollo 13 from mission control in episode 2x14 "Moonshot".
Kara and Mon-el head to the police parking garage where a group of officers is under attack by what appears to be Livewire in episode 2x10 "We Can Be Heroes".